Abstract: The radial gate of the discharge outlet on the left bank of Erlongshan Reservoir in Shaanxi Province was damaged due to the instability of the support arm. To investigate the primary causes behind the instability, we analyzed the strength and stability of the gate arm using the statics analysis module and linear eigenvalue buckling analysis module based on ANSYS following a comprehensive analysis of the accident site. Results indicate that the buckling failure of the gate arm occurred primarily due to inadequate sectional bending capacity. Based on these findings, we put forward recommendations regarding the renovation by using box beam arm structure. Subsequent verification demonstrates significant improvements in the strength and stability of the box beam structure arm, consequently meeting the specifications and safe operation requirements. The recommended method is of referential value for the safety evaluation and renovation of similar arc gates in other hydraulic engineering projects.

Key words: radial gate, instability of gate arm, renovation, ANSYS, Erlongshan Reservoir